Several analytical methods in molecular biology (e.g., sequencing library preparation) require that an adaptor is placed onto the end of a DNA fragment in order to provide a way to manipulate that fragment. For example, one or more adaptors may be ligated onto a fragment of DNA to produce an adaptor-ligated fragment, and the adaptor-ligated fragment may be amplified and/or sequenced using a primer binding site that is present in the added adaptor.